# Questions tagged [physics]

How physics applies to a particular activity in space or to getting to and from space.

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### Orbit Determination from Position and Velocity

I'm working on a game, somewhat similar to KSP (no building rockets, just beautiful orbital acrobatics). It's in a "small" star system, radius of 6 AU, and it features celestial bodies ...
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1 vote
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### How high will this rocket be, when MECO occurs?

Find the altitude of the rocket at the time of engine cut-off. Rocket Mass = 369208 kg, Rocket Area = 391 m2, Fuel = 170697 L, Fuel density = 21 kg/l, Exhaust Speed = 1338 m/s, Exhaust Area = 164 m2
183 views

### sun pointing coordinate system design

I am trying to program slew maneuver procedure for a spacecraft. My goal is to define a target coordinate system that is aligned with sun vector so that the spacecraft can slew its attitude to always ...
• 31
6k views

### Person falling from space

A person at rest 500 km above the Earth falls straight downwards. She has a snug magical force field around her that is totally rigid and completely protects her from outside heat. The force field ...
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### How much lead (kg) would you need to survive for an extended period of time in Jupiter’s radiation belts?

Imagine you have a 1 by 1 by 2 meter chamber that a human needs to survive in for one year, while orbiting in Jupiter’s radiation belts. How much lead, in weight, would have to surround the chamber to ...
256 views

### Converting Keplerian Orbital Elements into 2D State Vectors in Unity C#

I have done an extensive amount of research into this topic, but am really struggling to implement the math necessary to pull this off correctly. Just for some context: I'm trying to create a semi-...
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150 views

### What is missing in the conversion of specific impulse from units of seconds to thrust/mass flow rate? [duplicate]

I was trying to get the Specific Impulse of the Saturn V engines, hoping for a value in N/kg/s, as I need to know the mass consumption rate per thrust value. Any and all sources give me the value in ...
139 views

### Which notes and/or books on mathematics, physics, 3D geometry preparatory to the study of orbital dynamics?

I have a master's degree in aerospace engineering and I'm preparing for job interviews for orbital mechanics/space flight dynamics engineer positions and I need material about maths, physics, 3D ...
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### Why can't buoyancy of air be used to support a mega structure as an alternative to a space elevator?

The reason for asking this question stems from recent articles about large loss of strength of carbon nano tubes with even single atom movement, tested samples showing high vulnerability to space ...
• 99
249 views

### Will this homopolar motor self rotate in a vacuum?

Is it convenient to ask about the motor from the link: Roller Homopolar Motor When it is on the table, the motor rotates freely, together with the attached conductor. Will the upper motor in the ...
106 views

### Closed Loop Space propulsion

While browsing for Space propulsion found this book : https://www.knygos.lt/lt/knygos/closed-loop-space-propulsion-new-faster-approach-2e4zy/ Closed Loop Space Propulsion New Faster Approach : The ...
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230 views

### Is Electromagnetic Propulsion Like Radiation Pressure propulsion?

while browsing for new propulsion methods I found the following interesting: https://en.wikipedia.org/wiki/Radiation_pressure "Radiation pressure (also known as light pressure) is the mechanical ...
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### Calculating and Drawing the orbit of a body in a 2D gravity simulation in python

I'm making a space exploration game and its in a 2d plane so no z axis, and I'm using Newton's law of universal gravity, I would really like to calculate anddraw the predicted trajectory of a body, ...
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1 vote
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### What will be the escape velocity for a human body?

Now imagine an average man of 70kg floating in space with no gravitational forces acting on him. Now a pebble(25 grams) spawns into existence near him. So now there's a gravitational force between ...
787 views

### Is there less blue light available because the sky is blue? [closed]

Are the things we see that are blue .... less blue during daytime because the sky is blue (less blue light available to eluminate the ground)?
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1 vote
116 views

### When a spacecraft reaches the event horizon of a black hole, what happens to its residual gravitational potential energy?

A spacecraft falling from infinity directly towards a celestial body accelerates until it impacts the surface at the surface escape velocity. For any celestial body, the escape velocity is ...
• 21.4k
353 views

### Do larger less dense objects heat less while entering the atmophere?

When a space craft enters the atmosphere, it gets hot and heat shielding is needed. Do objects with more surface area and less density heat up less then heavier, smaller objects? Could an object with ...
1 vote
780 views

### Lorentz force space propulsion

While browsing for Space propulsion, I've found the following article As shown in Figure 2, the conductor I0 gets through the coil L0, and they are fixed together and form a system. a is the main ...
93 views

### Is it possible to avoid tearing apart from a blackhole if moving fast enough?

I have a spacecraft zooming directly into a blackhole with constant thrust. Considering the gravitational force of that blackhole and that there is no terminal velocity to slow me down. According a ...
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3k views

### Spacesuit with no thermal insulation. Would person inside freeze or overheat?

Let us say I have a theoretical super thin spacesuit which has zero thermal insulation. As if person would be naked in space, but all other variables - pressure, oxygen, food and other life support ...
• 355
149 views

### Two different Hill equations for space rendezvous

I have stumbled upon two variations of Hill’s equations across numerous scientific journals: Why are the mean motion’s positive and negative signs of these two Hill equations reversed? And are these ...
105 views

### Will the initial velocity of an object in space get multiplied if a constant acceleration is applied? [closed]

Imagine an object travelling in space in the speed of 60 Kmph which took acceleration x if accelerated with the same x, will the object travel faster than 60 Kmph or travel in the same speed cuz of ...
347 views

### What am I missing about rocket nozzle isentropic flow?

Playing a bit with Cpropep-Web, something looked wrong to me about how it models isentropic flow through a CD nozzle. I'm taking the RS-25 characteristics as an example. I ask for a frozen equilibrium ...
2k views

### If Earth had a second moon, where would it be positioned? [closed]

Could Earth theoretically have another moon, beside the existing one, that would have a stable orbit? If it is possible, could Newtonian physics describe where it would be (i.e its position relative ...
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1 vote
64 views

### Dependance of slosh mode on ratio of liquid height to tank height

If two liquid tanks of the same cross-section but different heights have the same liquid up to the same depth, will sloshing be the same or different in both tanks? I would assume they would be the ...
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265 views

### If anything, weren't the first people in orbit the first who broke the sound barrier in free fall?

Felix Baumgartner and Alan Eustace are said to have broken the sound barrier during their space jumps. But in space, there is no sound. In fact, they were still within the Earth's atmosphere so there ...
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136 views

### What is this thing that goes zipping past the Electron launch?

Watching the Electron launch 07 October 2022 on https://www.rocketlabusa.com/live-stream, what do I see in the video at T + 9:12, just after they confirm secondary engine cut off? I thought it was a ...
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656 views

### Satellite’s Position and Path on 2D Map [duplicate]

When the ISS orbit the Earth, its path traced on a 2D Mercator Earth Map is similar to a sinusoidal wave. I am wondering is there any way to determine the trig function of the wave, knowing the ...
129 views

### Ion propulsion system [duplicate]

Good evening. Is there a formulae to calculate how much lift an ion propulsion system would create on earth, given factors like voltage, load, etcetera? Just a mathematical formulae. That is all I ask ...
137 views

### How much solar radiation hits a spacecraft in transit to Mars?

How can I solve for the amount of radiation that hits a Mars transit vehicle, in transit? What formulas should I use? I am mostly focused on solar radiation.
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215 views

### How to calculate catalyst bed geometry (length/radius) for a monopropellant thruster?

Catalyst design is central to the development of monopropellant thrusters and hence, ignoring its importance, as I have realised, is not very good practice. My question is if the mass flow rate, bed ...
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### What is measured with g-forces?

When sitting at rest, a typical "g-meter" shows a value of one, however the meter is not accelerating. In orbit, it shows zero, but is under constant acceleration. The actual force of ...
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### Could a spacecraft theoretically fly a smooth, curved arc of a turn in space like an aircraft?

I understand there in no air is space which is what allows an aircraft to fly a curved flight path. This is strictly a theoretical question given today's technology. Here are the conditions: There ...
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591 views

### Inconsistencies in calculating exhaust velocity

I'm quite sure this is either a small or just plain stupid mistake but my anxiety is getting the better of me. when calculating exhaust velocity this is the equation used: however I keep getting ...
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### Gravitational field of the Moon and Earth

Is there any method to find a point or plane in space where the gravitational field of the Moon and Earth are the same? And if so, what happens to a spacecraft if it passes through that point or ...
1 vote
1k views

### How to plot a satellite's orbit around Earth in MATLAB?

Given orbit height, mass and initial velocity how should I plot a satellite's orbit in MATLAB? I was hoping to use verlet integration (I need to implement a solver) possibly the velocity-verlet. I ...
2k views

### How does Spinlaunch manage the counterweight right after launch?

Spinlaunch has successfully launched a suborbital test vehicle from a 1/3 scale demonstrator, see for instance aviationweek.com or space.com. While spinning up the arm, perfect balance is achieved ...
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### How much energy is lost by damping yaw from a SpinLaunch?

SpinLaunch hopes to launch a 200 kg satellite from a ground-based centrifuge, at 5000 mph, and more troublingly, at 450 rpm aka 7 tumbles per second. (The 3000 rpm figure mentioned in its tech sheets ...
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### Why is the sunny side of JWST's sunshield purple and covered with silicon?

After about 08:52 in Destin's Smarter Every Day's Why Are there Holes in the James Webb Sunshield? (Explained by My Dad) - Smarter Every Day 270 (linked below) ...
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### Why is the eccentricity vector used to describe near-circular orbits?

When dealing with near-circular orbits I've seen the usage of the eccentricity vector defined as $$(e_x,e_y) = (e\cos\omega, e\sin\omega)$$ I've seen this in Schaubs' "Analytical mechanics of ...
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454 views

### What do/will "quantum gyroscopes using nitro­gen-vacancy centers in diamond" for space applications actually look like, and how do they work?

The NASA page ELaNa 41 Mission has a section labeled QubeSat - University of California, Berkeley which says: QubeSat is a technology demonstration mission. It will test and character­ize the effects ...
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241 views

### To what percentage of the speed of light you need to accelerate to get artificial gravity at 1g?

Let's say you have a very powerful hypothetical fusion or matter/antimatter drive on a spaceship and you want to travel to a star nearby. Can you get 1g artificial gravity by accelerating? Or close to ...
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### Questions about orbital ring math from Birch 1982 paper

I have been reading the original Paul Birch paper published in JBIS 1982. I have been using this copy found here. In particular I am wondering about generalizing the ideas, like for a different planet ...
627 views

### How does gravity change beyond L2?

Why does gravity appear to increase again on the far side of L2 from earth as indicated on the gravitational contour diagram? One would expect gravity to continue to decrease as the distance from sun ...
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### Would the ship using the Alcubierre drive need to use conventional propulsion to move during warp? Or would the space-time "wave" push it?

I have found various explanations on how the warp drive works. And right now I'm confused. First I thought warp drive works by expanding space-time behind you, and contracting it in front of you. I ...
360 views

### Could you survive very high G's if your whole body was accelerated uniformly?

Could you survive high g's if your whole body was accelerated uniformly (not just by the seat of a rocket pushing on your back)? Your body is really only affected by gravity if you are touching ...
528 views

### Understanding g₀ to calculate delta-v

I am trying to calculate the exact delta-v from various existing upper stages with a given payload in a vaccum and in orbit, say LEO. I understand that according to the Tsiolkovsky rocket equation: \...
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### What can be determined about an orbit if it passes through two points

Using a 3D Cartesian coordinate system if we know for certain that a craft will pass through two points in it's orbit (let's call them p1 and p2) and we also know the mass of the central body it is ...
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1 vote